This
is the one which everybody knows. It breeds all over the worldin and around houses, rubbish dumps in
fact anywhere where there is decaying organic matter...and we certainly
throw plenty of that away. It has been suggested that this fly came originally
from Africa but nowadays it has followed us to all parts of the earth. In
Northern Europe it probably didn't become established until man started
keeping domestic animals indoors during the winter, a practice that didn't
start until about the beginning of the Iron Age, c. 400 B.C.

Life
Cycle and Description

The
housefly has a complete metamorphosis with distinct egg, larva or maggot,
pupal and adult stages. The house fly overwinters in either the larval or
pupal stage under manure piles or in other protected locations. Warm summer
conditions are generally optimum for the development of the house fly, and
it can complete its life cycle in as little as seven to ten days, and as
many as 10 to 12 generations may occur in one summer.

Egg:The white eggs, about 1.2 mm in length,
are laid singly but pile up in small masses. Each female fly can lay up
to 500 eggs in several batches of about 75 to 150 eggs, each over a three
to four day period. The number of eggs produced is a function of female
size, which is principally a result of larval nutrition.

Larva:The mature larva is 3 to 9 mm long, typical creamy whitish in color,
cylindrical but tapering toward the head. The head contains one pair of
dark hooks. The posterior spiracles are slightly raised and the spiracular
openings are sinuous slits which are completely surrounded by an oval black
border. The legless maggots emerge from the eggs in warm weather within
eight to 20 hours, and they immediately feed on and develop in the material
where the eggs were laid. The full-grown maggots have a greasy, cream-colored
appearance and are 8 to 12 mm long. The larvae go through three instars.
When the maggots are full-grown, they crawl up to 50 feet to a dried, cool
place near breeding material and transform to the pupal stage. High manure
moisture favors the survival of house fly larvae.

Pupa:The pupae are dark brown and 8 mm long. The pupal stage is passed in
a pupal case formed from the last larval skin which varies in color from
yellow, red, brown, to black as the pupa ages. The emerging fly escapes
from the pupal case through the use of an alternately swelling and shrinking
sac, called the ptilinum, on the front of its head which it uses like a
pneumatic hammer.

Adult:The house fly is 6 to 7 mm long, with the female usually larger than
the male. The eyes are reddish and the mouth parts are sponging. The thorax
bears four narrow black stripes and there is a sharp upward bend in the
fourth longitudinal wing vein. The abdomen is gray or yellowish with dark
midline and irregular dark markings on the sides. The underside of the male
is yellowish. The sexes can be readily separated by noting the space between
the eyes, which in females is almost twice as broad as in males.

Adults
usually live 15 to 25 days. The potential reproductive capacity of flies
is tremendous, but fortunately can never be realized. It has been stated
that a pair of flies beginning operations in April may be progenitors, if
all were to live, of 191,010,000,000,000,000,000, flies by August. Adults
suck liquids containing sweet or decaying substances. Larvae feed on moist
food rich in organic matter. Although they are attracted to a variety of
food material, house flies have mouth parts which allow them to ingest only
liquid materials. Solid materials are liquified by means of regurgitated
saliva. The flies are inactive at night, with ceilings, beams and overhead
wires within buildings, trees, and shrubs, various kinds of outdoor wires,
and grasses reported as overnight resting sites. In poultry ranches, the
outdoor aggregations of flies at night are found mainly in the branches,
and shrubs, whereas almost all of the indoor populations generally aggregated
in the ceiling area of poultry houses.

House
flies visit dung, carrion, and offal of all kinds and naturally they pick
up bacteria and viruses. They therefore act as carriers of diseases and
are wholly undesirable from a hygienic viewpoint. More
than 100 pathogens associated with the house fly may cause disease in humans
and animals, including typhoid, cholera, bacillary dysentery, tuberculosis,
anthrax ophthalmia and infantile diarrhea, as well as parasitic worms. Pathogenic
organisms are picked up by flies from garbage, sewage and other sources
of filth, and then transferred on their mouthparts and other body parts,
through their vomitus, faeces and contaminated external body parts to human
and animal food.In
addition they can be intensely irritating when they occur in great swarms,
settling on man and beast alike.

Damage

Flies
commonly develop in large numbers in poultry manure under caged hens, and
this is a serious problem requiring control. The control ofMusca domesticais
vital to human health and comfort in many areas of the world. The most important
damage related with this insect is the annoyance and the indirect damage
produced by the potential transmission of more than 100 pathogens associated
with this fly.

Economic
Injury Level

The
threshold density for determining when to control flies depends on the area
where the control measures will be taken. In general, at homes the threshold
is very low and control actions are taken with few flies The complaint threshold
density of the house fly at waste management sites may be 150 individuals
per flypaper per 30 minutes. House flies are monitored with baited traps,
sticky ribbons, or spot cards on livestock facilities. Spot cards are 3-inch
by 5-inch white index cards attached to fly resting surface. A minimum of
five cards should be placed in each animal facility and left in place for
seven days. A count of 100 or more fecal or vomit spots per card per week
indicates a high level of fly activity and a need for control.

ManagementThe more common control measures involved with the control
of house flies are sanitation, use of traps, and insecticides, but in some
instances integrated fly control has been implemented. The use of biological
control in fly management is still at a relatively early stage.

Sanitation or Cultural Control:Good
sanitation is the basic step in all fly management. Food and materials on
which the flies can lay their eggs must be removed, destroyed as a breeding
medium, or isolated from the egg-laying adult. Since the house fly can complete
its life cycle in as little as seven days, removal of wet manure at least
twice a week is necessary to break the breeding cycle. Wet straw should
not be allowed to pile up in or near buildings. Since straw is one of the
best fly breeding materials, it is not recommended as bedding. Spilled feed
should not be allowed to accumulate but should be cleaned up two times a
week. Ordinarily, fly control from 1 to 2 km around a municipality will
prevent ingress of the house fly into a municipality. Killing adult flies
may reduce the infestation, but elimination of breeding areas is necessary
for good management. Garbage cans and skips should have tight-fitting lids
and be cleaned regularly. Dry and wet rubbish should be placed in plastic
rubbish bags and sealed up. All waste receptacles should be located as far
from building entrances as possible. For control at waste disposal sites,
refuse should be deposited onto the same area as inorganic wastes to deteriorate
the capacity of breeding resources, or the disposed refuse should be covered
with soil or other inorganic wastes (15 cm thickness) on every weekend or
every other weekend.

Traps:Fly traps may be useful in
some fly control programs if enough traps are used, if they are placed correctly,
and if they are used both indoors and outdoors. House flies are attracted
to white surfaces and to baits that give off odors. Indoors, ultraviolet
light traps collect the flies inside an inverted cone or kill them with
an electrocuting grid. One trap should be placed for every 30 feet of wall
inside buildings, but not placed over or within five feet of food preparation
areas. Recommended placement areas outdoors include near building entrances,
in alleyways, beneath trees, and around animal sleeping areas and manure
piles. Openings to buildings should be tightly screened with standard window
screen, thereby denying entrance to flies.

Biological Control:With increasing
incidence of insecticide resistant house fly populations, rising costs of
insecticides and a growing public concern about actual or potential problems
associated with insecticides, interest in alternative house fly control
strategies has increased.

Integrated
fly control:Integrated fly control programs for caged-poultry
houses are based on the following strategy 1) selective applications of
insecticides against the adult, 2) start insecticide control measures early
in the spring before flies appeared and repeated as frequently as needed
through the warm months, and 3) the manure is left undisturbed throughout
the warm months when fly breeding may occur. The manure would be removed
once very early in the spring before any flies appear.

Insecticides:When the house fly is a mayor pest in commercial egg production facilities,
the control of this insect is by the application of adulticides, or larvicides
to directly or indirectly suppress adult densities. Residual wall sprays
can be applied where the flies congregate. Resistance to permethrin develops
more rapidly in fly populations from farms on a continuous permethrin regime
than in farms in which permethrin and diclorvos have been alternated.

Outdoors, the control of flies includes the use of boric acid in the
bottom of skips, treatment of vertical walls adjacent to skips and other
breeding sites with microencapsulated or wettable powder formulation, and
the use of fly baits near adult feeding sources. In areas like rubbish tips
dusting powders can be used, applied with a machine called a MotoBlo, which
gives dispersal over a large area. This treatment should always be carried
out by a registered pest control company as there are many regulations to
be observed.

Indoors, the control of flies includes automatic misters, fly paper,
electrocuting and baited traps that can be used in milking parlours and
other areas of low fly numbers.

Sometimes
tiny invertebrates can be found hanging on to the legs and abdomen of
the fly. These may be mites of various kinds or false scorpions. This
is how this type of small insect is transported from place to place.
In all cases these are species which live on or near dung where the
flies develop and they only release their grip when they come near more
manure....a scented existence...so there is no danger of them becoming
established indoors...